Mocvd single chamber split process for led manufacturing

ABSTRACT

In one embodiment an integrated processing system for manufacturing compound nitride semiconductor devices comprising a metal organic chemical vapor deposition (MOCVD) chamber operable to form a gallium nitride (GaN) layer over one or more substrates with a thermal chemical-vapor-deposition process and to form a multi-quantum well (MQW) layer over the GaN layer, and a halogen containing gas source coupled with the MOCVD chamber operable for flowing a halogen containing gas into the MOCVD chamber to remove at least a portion of unwanted deposition build-up deposited when forming the GaN layer over the one or more substrate from one or more interior surfaces of the MOCVD chamber prior to forming the MQW layer over the GaN layer, wherein the halogen containing gas is selected from the group comprising fluorine, chlorine, bromine, iodine, HI gas, HCl gas, HBr gas, HF gas, NF3, and combinations thereof is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of co-pending U.S. patentapplication Ser. No. 12/730,975 (Attorney Docket No. APPM/014309), filedon Mar. 24, 2010, which claims benefit of U.S. Provisional PatentApplication Ser. No. 61/173,552 (APPM/014309L), filed Apr. 28, 2009,which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to themanufacturing of devices, such as light emitting diodes (LEDs), laserdiodes (LDs) and, more particularly, to processes for forming GroupIII-V materials by metal-organic chemical vapor deposition (MOCVD)deposition processes.

2. Description of the Related Art

Group III-V films are finding greater importance in the development andfabrication of a variety of semiconductor devices, such as shortwavelength LEDs, LDs, and electronic devices including high power, highfrequency, high temperature transistors and integrated circuits. Forexample, short wavelength (e.g., blue/green to ultraviolet) LEDs arefabricated using the Group III-nitride semiconducting material galliumnitride (GaN). It has been observed that short wavelength LEDsfabricated using GaN can provide significantly greater efficiencies andlonger operating lifetimes than short wavelength LEDs fabricated usingnon-nitride semiconducting materials, comprising Group II-VI elements.

One method that has been used for depositing Group III-nitrides, such asGaN, is metal organic chemical vapor deposition (MOCVD). This chemicalvapor deposition method is generally performed in a reactor having atemperature controlled environment to assure the stability of a firstprecursor gas which contains at least one element from Group III, suchas gallium (Ga). A second precursor gas, such as ammonia (NH₃), providesthe nitrogen needed to form a Group III-nitride. The two precursor gasesare injected into a processing zone within the reactor where they mixand move towards a heated substrate in the processing zone. A carriergas may be used to assist in the transport of the precursor gasestowards the substrate. The precursors react at the surface of the heatedsubstrate to form a Group III-nitride layer, such as GaN, on thesubstrate surface. The quality of the film depends in part upondeposition uniformity which, in turn, depends upon uniform flow andmixing of the precursors across the substrate.

Unwanted deposition on the interior surfaces such as the walls and theshowerheads of the MOCVD processing chambers may occur during MOCVDprocesses. Such unwanted deposition may create particles and flakeswithin the chamber, resulting in the drift of process conditions andmore importantly affecting the process reproducibility and uniformity.

As the demand for LEDs, LDs, transistors, and integrated circuitsincreases, the efficiency of depositing high quality Group-III nitridefilms takes on greater importance. Therefore, there is a need for animproved process and apparatus that can provide consistent film qualityover larger substrates and larger deposition areas.

SUMMARY OF THE INVENTION

Embodiments described herein generally relate to methods for formingGroup III-V materials by metal-organic chemical vapor deposition (MOCVD)processes. In one embodiment, a method for fabricating a compoundnitride semiconductor structure is provided. The method comprisesdepositing a first layer over one or more substrates with a thermalchemical-vapor-deposition process within a processing chamber using afirst group-III precursor comprising a first group-III element and afirst nitrogen containing precursor, wherein the first layer comprisesnitrogen and the first group-III element, removing the one or moresubstrates from the processing chamber after depositing a first layerwithout exposing the one or more substrates to atmosphere, flowing afirst cleaning gas into the processing chamber to remove contaminantsfrom the processing chamber after removing the one or more substratesfrom the processing chamber after depositing a first layer, transferringthe one or more substrates into the processing chamber without exposingthe one or more substrates to atmosphere after removing contaminantsfrom the processing chamber; and depositing a second layer over thefirst layer with a thermal chemical-vapor-deposition process within theprocessing chamber using a second group-III precursor and a secondnitrogen containing precursor, wherein the second group-III precursorcomprises a second group-III element not comprised by the firstgroup-III precursor.

In another embodiment, a method for fabricating a compound nitridesemiconductor structure is provided. The method comprises positioningone or more substrates on a susceptor in a processing region of a metalorganic chemical vapor deposition (MOCVD) chamber comprising ashowerhead, depositing a gallium nitride layer over the substrate with athermal chemical-vapor-deposition process within the MOCVD chamber byflowing a first gallium containing precursor and a first nitrogencontaining precursor through the showerhead into the MOCVD chamber,removing the one or more substrates from the MOCVD chamber withoutexposing the one or more substrates to atmosphere, flowing a chlorinegas into the processing chamber to remove contaminants from theshowerhead, transferring the one or more substrates into the MOCVDchamber after removing contaminants from the showerhead; and depositingan InGaN layer over the GaN layer with a thermalchemical-vapor-deposition process within the MOCVD chamber by flowing asecond gallium containing precursor, an indium containing precursor, anda second nitrogen containing precursor into the MOCVD chamber.

In yet another embodiment, an integrated processing system formanufacturing compound nitride semiconductor devices is provided. Theintegrated processing system comprises a metal organic chemical vapordeposition (MOCVD) operable to form a gallium nitride (GaN) layer overone or more substrates with a thermal chemical-vapor-deposition processand to form a multi-quantum well (MQW) layer over the GaN layer and ahalogen containing gas source coupled with the MOCVD chamber operablefor flowing a halogen containing gas into the MOCVD chamber to remove atleast a portion of unwanted deposition build-up deposited when formingthe GaN layer over the one or more substrate from one or more interiorsurfaces of the MOCVD chamber prior to forming the MQW layer over theGaN layer, wherein the halogen containing gas is selected from the groupcomprising fluorine, chlorine, bromine, iodine, HI gas, HCl gas, HBrgas, HF gas, NF₃, and combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is a schematic illustration of a structure of a GaN-based LED;

FIG. 1B is an EDX spectrum of showerhead deposition after growth of aLED structure;

FIG. 1C is a gallium-indium phase diagram;

FIG. 2 is a schematic top view illustrating one embodiment of aprocessing system for fabricating compound nitride semiconductor devicesaccording to embodiments described herein;

FIG. 3 is a schematic cross-sectional view of a metal-organic chemicalvapor deposition (MOCVD) chamber for fabricating compound nitridesemiconductor devices according to embodiments described herein;

FIG. 4 is a flow diagram of a process that may be used for singlechamber compound nitride semiconductor formation according toembodiments described herein;

FIG. 5 is a flow diagram of a cleaning process that may be used forMOCVD chamber cleaning according to embodiments described herein;

FIG. 6A is a plot demonstrating In X-Ray Fluorescence for Indistribution across the surface of a substrate for In deposited usingprior art processes; and

FIG. 6B is a plot demonstrating In X-Ray Fluorescence for indiumdistribution across the surface of a substrate for indium depositedaccording to embodiments described herein.

DETAILED DESCRIPTION

Embodiments described herein generally relate to methods for formingGroup III-V materials by MOCVD processes. In one embodiment, an in-situchamber clean process is performed after deposition of a III₁-N layer ona substrate and prior to deposition of a III₂-N layer on the substratein the same chamber. In one embodiment an in-situ chamber clean processis performed after a high temperature GaN deposition process and priorto InGaN multi-quantum well (MQW), AlGaN, and pGaN growth in the samechamber. It has been found by the inventors that performing MQWdeposition in the same chamber as GaN deposition after an in-situchamber clean process eliminates indium depletion in the gas phase. As aresult, tri-methyl indium (TMI) input flow is also significantlyreduced, for example, a TMI flow rate of 400-500 sccm is used for InGaNMQW growth after performing the chamber clean process as compared to aflow rate of 800-1200 sccm for in-situ InGaN MQW growth performedwithout the chamber clean process. Moreover, after a chamber cleanprocess, indium deposition is more uniform across the substrate whichresults in desirable photoluminescence (PL) wavelength uniformity. Inone embodiment, the chamber clean process is performed by flowing ahalogen containing cleaning gas, such as chlorine gas, into the MOCVDchamber to convert the gallium coating on the surfaces of the chamberand the chamber components into GaCl₃ which may then be removed from thechamber.

While the particular apparatus in which the embodiments described hereincan be practiced is not limited, it is particularly beneficial topractice the embodiments in a cluster tool system sold by AppliedMaterials, Inc., Santa Clara, Calif. Additionally, systems availablefrom other manufacturers including linear systems may also benefit fromembodiments described herein.

Currently, MOCVD techniques are the most widely used techniques for thegrowth of Group III-nitride based LED manufacturing. One typicalnitride-based structure is illustrated in FIG. 1A as a GaN-based LEDstructure 100. It is fabricated over a substrate 104. Substrate size mayrange from 50 mm-100 mm in diameter or larger. It is to be understoodthat the substrates may consist of at least one of sapphire, SiC, GaN,silicon, quartz, GaAs, AlN, and glass. An undoped gallium nitride (u-GaNlayer) followed by an n-type GaN layer 112 is deposited over an optionalbuffer layer 109 (e.g. GaN) and/or an optional seed/nucleation layer 108(e.g. aluminum nitride (AlN) formed over the substrate. In oneembodiment, the nucleation layer 108 comprises Al_(x)Ga_(1-x)N and thesubstrate 104 comprises AlN. In another embodiment, the buffer layer 109comprises GaN and is deposited on the nucleation layer 108 whichcomprises Al_(x)Ga_(1-x)N. An active region of the device is embodied ina multi-quantum-well layer 116, shown in the drawing to comprise anInGaN layer. A p-n junction is formed with an overlying p-type AlGaNlayer 120, with a p-type GaN layer 124 acting as a contact layer.

A typical fabrication process for such an LED may use a MOCVD processthat follows cleaning of the substrate 104 in a processing chamber. TheMOCVD deposition is accomplished by providing flows of suitableprecursors to the processing chamber and using thermal processes toachieve deposition. For example, a GaN layer may be deposited using Gaand nitrogen containing precursors, perhaps with a flow of a fluent gaslike N₂, H₂, and NH₃. An InGaN layer may be deposited using Ga, N, andIn precursors, perhaps with a flow of a fluent gas. An AlGaN layer maybe deposited using Ga, N, and Al precursors, also perhaps with a flow ofa fluent gas. In the illustrated structure 100, the GaN buffer layer 108has a thickness of about 500 Å, and may have been deposited at atemperature of about 550° C. Subsequent deposition of the u-GaN andn-GaN layer 112 is typically performed at a higher temperature, such asaround 1,050° C. in one embodiment. The u-GaN and n-GaN layer 112 isrelatively thick. In one embodiment, the u-GaN and n-GaN layer has athickness on the order of about 4 μm requiring about 140 minutes fordeposition. In one embodiment, the InGaN multi-quantum-well (MQW) layer116 may have a thickness of about 750 Å, which may be deposited over aperiod of about 40 minutes at a temperature of about 750° C. In oneembodiment, the p-AlGaN layer 120 may have a thickness of about 200 Å,which may be deposited in about five minutes at a temperature from about950° C. to about 1,020° C. In one embodiment, the thickness of thecontact layer 124 that completes the structure may be about 0.4 μm, andmay be deposited at a temperature of about 1,050° C. for around 25minutes. Additionally, dopants, such as silicon (Si) or magnesium (Mg),may be added to the films. The films may be doped by adding smallamounts of dopant gases during the deposition process. For silicondoping, silane (SiH₄) or disilane (Si₂H₆) gases may be used, forexample, and a dopant gas may include Bis(cyclopentadienyl) magnesium(Cp₂Mg or (C₅H₅)₂Mg) for magnesium doping.

When the aforementioned steps are performed in a single MOCVD chamber,the growth of GaN at high temperatures results in severe parasiticdeposition of Ga metal and GaN within the MOCVD chamber, especially onchamber components including the showerhead or gas distribution assemblyof the MOCVD chamber. As shown in FIG. 1B, this parasitic deposition isgenerally rich in gallium. Gallium rich depositions cause problems dueto the nature of gallium itself which acts as a trap, reacting with thegas phase precursors used for deposition of subsequent single layers ofLED, such as, for example, tri-methyl indium (TMI), tri-methyl aluminum(TMA), n-type dopants such as silane (SiH₄) and disilane (Si₂H₆), andp-type dopants such as Cp₂Mg. InGaN multi-quantum wells (MQW) are themost affected due to Ga—In eutectic formation, shown in FIG. 1C, atfavorable conditions within the MOCVD chamber leading to PL wavelengthdrift, PL intensity reduction, and device degradation in general.

FIG. 2 is a schematic top view illustrating one embodiment of aprocessing system 200 that comprises a single MOCVD chamber 202 forfabricating compound nitride semiconductor devices according toembodiments described herein. In one embodiment, the processing system200 is closed to atmosphere. Although one MOCVD chamber 202 is shown, itshould be understood that more than one MOCVD chamber 202 oradditionally, combinations of one or more MOCVD chambers 202 with one ormore Hydride Vapor Phase Epitaxial (HVPE) chamber may also be coupledwith the transfer chamber 206. The processing system 200 comprises atransfer chamber 206 housing a substrate handler (not shown), a MOCVDchamber 202 coupled with the transfer chamber 206, a loadlock chamber208 coupled with the transfer chamber 206, a batch loadlock chamber 209,for storing substrates, coupled with the transfer chamber 206, and aload station 210, for loading substrates, coupled with the loadlockchamber 208. The transfer chamber 206 comprises a robot assembly (notshown) operable to pick up and transfer substrates between the loadlockchamber 208, the batch loadlock chamber 209, and the MOCVD chamber 202.It should also be understood that although a cluster tool is shown, theembodiments described herein may be performed using linear tracksystems.

The transfer chamber 206 may remain under vacuum during the process. Thetransfer chamber vacuum level may be adjusted to match the vacuum levelof the MOCVD chamber 202. For example, when transferring a substratefrom a transfer chamber 206 into the MOCVD chamber 202 (or vice versa),the transfer chamber 206 and the MOCVD chamber 202 may be maintained atthe same vacuum level. Then, when transferring a substrate from thetransfer chamber 206 to the load lock chamber 208 or batch load lockchamber 209 (or vice versa), the transfer chamber vacuum level may matchthe vacuum level of the loadlock chamber 208 or batch load lock chamber209 even through the vacuum level of the loadlock chamber 208 or batchload lock chamber 209 and the MOCVD chamber 202 may be different. Thus,the vacuum level of the transfer chamber may be adjusted. In certainembodiments, the substrate is transferred in a high purity inert gasenvironment, such as, a high purity N₂ environment. In one embodiment,the substrate is transferred in an environment having greater than 90%N₂. In certain embodiments, the substrate is transferred in a highpurity NH₃ environment. In one embodiment, the substrate is transferredin an environment having greater than 90% NH₃. In certain embodiments,the substrate is transferred in a high purity H₂ environment. In oneembodiment, the substrate is transferred in an environment havinggreater than 90% H₂.

In the processing system 200, the robot assembly transfers a substratecarrier plate 212 loaded with substrates into the single MOCVD chamber202 to undergo deposition. In one embodiment, the substrate carrierplate 212 may range from 200 mm-750 mm. The substrate carrier may beformed from a variety of materials, including SiC or SiC-coatedgraphite. In one embodiment, the carrier plate 212 comprises a siliconcarbide material. In one embodiment, the carrier plate 212 has a surfacearea of about 1,000 cm² or more, preferably 2,000 cm² or more, and morepreferably 4,000 cm² or more. After all or some of the deposition stepshave been completed, the carrier plate 212 is transferred from the MOCVDchamber 202 back to the loadlock chamber 208. In one embodiment, thecarrier plate 212 is then released toward the load station 210. Inanother embodiment, the carrier plate 212 may be stored in either theloadlock chamber 208 or the batch load lock chamber 209 prior to furtherprocessing in the MOCVD chamber 202. One exemplary system is describedin U.S. patent application Ser. No. 12/023,572, filed Jan. 31, 2008, nowpublished as US 2009-0194026, titled PROCESSING SYSTEM FOR FABRICATINGCOMPOUND NITRIDE SEMICONDUCTOR DEVICES, which is hereby incorporated byreference in its entirety.

A system controller 260 controls activities and operating parameters ofthe processing system 200. The system controller 260 includes a computerprocessor and a computer-readable memory coupled to the processor. Theprocessor executes system control software, such as a computer programstored in memory. Aspects of the processing system and methods of useare further described in U.S. patent application Ser. No. 11/404,516,filed Apr. 14, 2006, now published as US 2007-024,516, titled EPITAXIALGROWTH OF COMPOUND NITRIDE STRUCTURES, which is hereby incorporated byreference in its entirety.

FIG. 3 is a schematic cross-sectional view of an MOCVD chamber accordingto embodiments described herein. The MOCVD chamber 202 comprises achamber body 302, a chemical delivery module 303 for deliveringprecursor gases, carrier gases, cleaning gases, and/or purge gases, aremote plasma system 326 with a plasma source, a susceptor or substratesupport 314, and a vacuum system 312. The chamber 202 includes a chamberbody 302 that encloses a processing volume 308. A showerhead assembly304 is disposed at one end of the processing volume 308, and the carrierplate 212 is disposed at the other end of the processing volume 308. Thecarrier plate 212 may be disposed on the substrate support 314. Thesubstrate support 314 has z-lift capability for moving in a verticaldirection, as shown by arrow 315. In one embodiment, the z-liftcapability may be used to move the substrate support either upward andcloser to the showerhead assembly 304 or downward and further away fromthe showerhead assembly 304. In certain embodiments, the substratesupport 314 comprises a heating element, for example, a resistiveheating element (not shown) for controlling the temperature of thesubstrate support 314 and consequently controlling the temperature ofthe carrier plate 212 and substrates 340 positioned on the substratesupport 314.

In one embodiment, the showerhead assembly 304 has a first processinggas channel 304A coupled with the chemical delivery module 303 fordelivering a first precursor or first process gas mixture to theprocessing volume 308, a second processing gas channel 304B coupled withthe chemical delivery module 303 for delivering a second precursor orsecond process gas mixture to the processing volume 308 and atemperature control channel 304C coupled with a heat exchanging system370 for flowing a heat exchanging fluid to the showerhead assembly 304to help regulate the temperature of the showerhead assembly 304.Suitable heat exchanging fluids include but are not limited to water,water-based ethylene glycol mixtures, a perfluoropolyether (e.g. Galden®fluid), oil-based thermal transfer fluids, or similar fluids. In oneembodiment, during processing the first precursor or first process gasmixture may be delivered to the processing volume 308 via gas conduits346 coupled with the first processing gas channel 304A in the showerheadassembly 304 and the second precursor or second process gas mixture maybe delivered to the processing volume 308 via gas conduits 345 coupledwith the second gas processing channel 304B. In embodiments where theremote plasma source is used, the plasma may be delivered to theprocessing volume 308 via conduit 304D. It should be noted that theprocess gas mixtures or precursors may comprise one or more precursorgases or process gases as well as carrier gases and dopant gases whichmay be mixed with the precursor gases. Exemplary showerheads that may beadapted to practice embodiments described herein are described in U.S.patent application Ser. No. 11/873,132, filed Oct. 16, 2007, nowpublished as US 2009-0098276, entitled MULTI-GAS STRAIGHT CHANNELSHOWERHEAD, U.S. patent application Ser. No. 11/873,141, filed Oct. 16,2007, now published as US 2009-0095222, entitled MULTI-GAS SPIRALCHANNEL SHOWERHEAD, and U.S. patent application Ser. No. 11/873,170,filed Oct. 16, 2007, now published as US 2009-0095221, entitledMULTI-GAS CONCENTRIC INJECTION SHOWERHEAD, all of which are incorporatedby reference in their entireties.

A lower dome 319 is disposed at one end of a lower volume 310, and thecarrier plate 212 is disposed at the other end of the lower volume 310.The carrier plate 212 is shown in process position, but may be moved toa lower position where, for example, the substrates 340 may be loaded orunloaded. An exhaust ring 320 may be disposed around the periphery ofthe carrier plate 212 to help prevent deposition from occurring in thelower volume 310 and also help direct exhaust gases from the chamber 202to exhaust ports 309. The lower dome 319 may be made of transparentmaterial, such as high-purity quartz, to allow light to pass through forradiant heating of the substrates 340. The radiant heating may beprovided by a plurality of inner lamps 321A and outer lamps 321Bdisposed below the lower dome 319 and reflectors 366 may be used to helpcontrol the chamber 202 exposure to the radiant energy provided by innerand outer lamps 321A, 321B. Additional rings of lamps may also be usedfor finer temperature control of the substrates 340.

In certain embodiments, a purge gas (e.g., a nitrogen containing gas)may be delivered into the chamber 202 from the showerhead assembly 304and/or from inlet ports or tubes (not shown) disposed below the carrierplate 212 and near the bottom of the chamber body 302. The purge gasenters the lower volume 310 of the chamber 202 and flows upwards pastthe carrier plate 212 and exhaust ring 320 and into multiple exhaustports 309 which are disposed around an annular exhaust channel 305. Anexhaust conduit 306 connects the annular exhaust channel 305 to a vacuumsystem 312 which includes a vacuum pump 307. The chamber 202 pressuremay be controlled using a valve system which controls the rate at whichthe exhaust gases are drawn from the annular exhaust channel. Otheraspects of the MOCVD chamber are described in U.S. patent applicationSer. No. 12/023,520, filed Jan. 31, 2008, published as US 2009-0194024,and titled CVD APPARATUS, which is herein incorporated by reference inits entirety.

In certain embodiments, a cleaning gas (e.g., a halogen containing gas,such as chlorine gas) may be delivered into the chamber 202 from theshowerhead assembly 304 and/or from inlet ports or tubes (not shown)disposed near the processing volume 308. The cleaning gas enters theprocessing volume 308 of the chamber 202 to remove deposits from chambercomponents such as the substrate support 314 and the showerhead assembly304 and exits the chamber via multiple exhaust ports 309 which aredisposed around the annular exhaust channel 305.

The chemical delivery module 303 supplies chemicals to the MOCVD chamber202. Reactive gases, carrier gases, purge gases, and cleaning gases maybe supplied from the chemical delivery system through supply lines andinto the chamber 202. In one embodiment, the gases are supplied throughsupply lines and into a gas mixing box where they are mixed together anddelivered to the showerhead assembly 304. Generally supply lines foreach of the gases include shut-off valves that can be used toautomatically or manually shut-off the flow of the gas into itsassociated line, and mass flow controllers or other types of controllersthat measure the flow of gas or liquid through the supply lines. Supplylines for each of the gases may also include concentration monitors formonitoring precursor concentrations and providing real time feedback,backpressure regulators may be included to control precursor gasconcentrations, valve switching control may be used for quick andaccurate valve switching capability, moisture sensors in the gas linesmeasure water levels and can provide feedback to the system softwarewhich in turn can provide warnings/alerts to operators. The gas linesmay also be heated to prevent precursors and cleaning gases fromcondensing in the supply lines. Depending upon the process used some ofthe sources may be liquid rather than gas. When liquid sources are used,the chemical delivery module includes a liquid injection system or otherappropriate mechanism (e.g. a bubbler) to vaporize the liquid. Vaporfrom the liquids is then usually mixed with a carrier gas as would beunderstood by a person of skill in the art.

Remote microwave plasma system 326 can produce a plasma for selectedapplications, such as chamber cleaning or etching residue from a processsubstrate. Plasma species produced in the remote plasma system 326 fromprecursors supplied via an input line are sent via a conduit fordispersion through the showerhead assembly 304 to the MOCVD chamber 202via conduit 304D. Precursor gases for a cleaning application may includechlorine containing gases, fluorine containing gases, iodine containinggases, bromine containing gases, nitrogen containing gases, and/or otherreactive elements. The remote microwave plasma system 326 may also beadapted to deposit CVD layers flowing appropriate deposition precursorgases into remote microwave plasma system 326 during a layer depositionprocess. In one embodiment, the remote microwave plasma system 326 isused to deliver active chlorine species to the processing volume 308 forcleaning the interior of the MOCVD chamber 202.

The temperature of the walls of the MOCVD chamber 202 and surroundingstructures, such as the exhaust passageway, may be further controlled bycirculating a heat-exchange liquid through channels (not shown) in thewalls of the chamber. The heat-exchange liquid can be used to heat orcool the chamber walls depending on the desired effect. For example, hotliquid may help maintain an even thermal gradient during a thermaldeposition process, whereas a cool liquid may be used to remove heatfrom the system during an in-situ plasma process, or to limit formationof deposition products on the walls of the chamber. This heating,referred to as heating by the “heat exchanger”, beneficially reduces oreliminates condensation of undesirable reactant products and improvesthe elimination of volatile products of the process gases and othercontaminants that might contaminate the process if they were to condenseon the walls of cool vacuum passages and migrate back into theprocessing chamber during periods of no gas flow.

Split Process:

FIG. 4 is a flow diagram of a process 400 that may be used for singlechamber compound nitride semiconductor formation according toembodiments described herein. The process begins at block 404 bytransferring a substrate into a substrate processing chamber. It shouldbe understood that “a substrate” includes “one or more substrates.” Inone embodiment, the substrate processing chamber is similar to MOCVDchamber 202. For deposition of a nitride structure, the substrate maycomprise sapphire, although other materials that may be used includeSiC, Si, spinel, lithium gallate, ZnO, and others. The substrate iscleaned at block 408, after which process parameters suitable for growthof a nitride layer may be established at block 412. Such processparameters may include temperature, pressure, and the like to define anenvironment within the processing chamber appropriate for thermaldeposition of a nitride layer. Flows of precursors are provided at block416 on the substrate to deposit III₁-N structures on the substrate atblock 420. The precursors include a nitrogen source and a source for afirst group-III element such as Ga. For instance, suitable nitrogenprecursors include NH₃ and suitable Ga precursors include trimethylgallium (“TMG”) and triethyl gallium (TEG). The first group-III elementmay sometimes comprise a plurality of distinct group-III elements suchas Al and Ga, in which case a suitable Al precursor may be trimethylaluminum (“TMA”). In another example, the plurality of distinctgroup-III elements includes In and Ga, in which case a suitable Inprecursor may be trimethyl indium (“TMI”). A flow of one or more carriergases selected from the group of argon, nitrogen, hydrogen, helium,neon, xenon, and combinations thereof may also be included.

After deposition of the III₁-N structure at block 420, the precursorflows are terminated at block 424. The substrate is removed from theprocessing chamber without exposing the substrate to atmosphere at block426. Removing the substrate from the processing chamber without brakingvacuum prevents exposure of the deposited III₁-N structure to oxygen andcarbon which act as electrically active dopants/impurities. At block428, a cleaning process is performed in which the interior of theprocessing chamber is exposed to a first cleaning gas to removecontaminants, such as gallium containing deposits, from the chamber andchamber components. In one embodiment, the cleaning process may compriseexposing the chamber to etchant gases which thermally etch depositionfrom chamber walls and surfaces. Optionally, the processing chamber maybe exposed to a plasma during the cleaning process. Cleaning gases forthe cleaning process may include halogen containing gases such asfluorine gas (F₂), chlorine gas (Cl₂), bromine gas (Br₂), iodine gas(I₂), HI gas, HCl gas, HBr gas, HF gas, NF₃, and/or other reactiveelements. A flow of one or more carrier gases selected from the group ofargon, nitrogen, hydrogen, helium, neon, xenon, and combinations thereofmay also be included. In one embodiment, the cleaning process comprisesexposing the chamber to a plasma. In one embodiment, the plasma isgenerated by a remote plasma generator. In another embodiment, theplasma is generated in-situ.

After cleaning, the substrate is transferred back into the processingchamber at block 430 and subsequent deposition steps are performed inthe same processing chamber. A III₂-N layer is deposited over the III₁-Nlayer on the substrate at block 432.

Deposition of the III₂-N layer is performed by establishing suitableprocessing parameters such as temperature, pressure, and the like forsuch deposition. In some embodiments, the III₂-N structure includes agroup-III element that is not comprised by the III₁-N layer, althoughthe III₁-N and III₂-N layers may additionally comprise a commongroup-III element. For instance, in the case where the III₁-N layer isGaN, the III₂-N layer may be an AlGaN layer or an InGaN layer. Whilethese are examples in which the III₂-N layer has a ternary composition,this is not required and the III₂ layer may more generally include suchother compositions as quaternary AlInGaN layers. Similarly, inembodiments where the III₁-N layer is AlGaN, the III₂-N layer may be anInGaN layer on an AlInGaN layer. Suitable precursors for deposition ofthe III₂-N layer may be similar to the precursors used for the III₁-Nlayer, i.e. NH₃ is a suitable nitrogen precursor, TMG is a suitablegallium precursor, TEG is a suitable gallium precursor, TMA is asuitable aluminum precursor, and TMI is a suitable indium precursor. Aflow of one or more carrier gases selected from the group of argon,nitrogen, hydrogen, helium, neon, xenon, and combinations thereof mayalso be included.

After deposition of the III₂-N layer at block 432, the precursor flowsare terminated at block 438. Optionally, the one or more substrates areremoved from the processing chamber without exposing the one or moresubstrates to atmosphere at block 440. Removing the one or moresubstrates from the processing chamber without braking vacuum preventsexposure of the deposited III₂-N structure to oxygen and carbon whichact as electrically active dopants/impurities. At block 442, an optionalcleaning process may be performed in which the interior of theprocessing chamber is exposed to a second cleaning gas to removecontaminants, such as group III containing deposits, from the chamberand chamber components.

At block 444, the substrate is transferred under vacuum into thesubstrate processing chamber. After the one or more substrates aretransferred into the processing chamber at block 444 subsequentdeposition steps are performed in the processing chamber.

At block 446, process parameters suitable for growth of a III₃-N layermay be established. Deposition of the III₃-N layer is performed byestablishing suitable processing parameters such as temperature,pressure, and the like for such deposition. In some embodiments, theIII₃-N structure includes a group-III element that is not comprised byeither the III₁-N layer or the III₂-N layer, although the III₁-N, theIII₂-N, and III₃-N layers may additionally comprise a common group-IIIelement. For instance, in the case where the III₁-N layer is GaN, theIII₂-N layer may be an InGaN layer, and the III₃-N layer may be an AlGaNlayer. While these are examples in which the III₃-N layer has a ternarycomposition, this is not required and the III₃-N layer may moregenerally include such other compositions as quaternary AlInGaN layers.Suitable precursors for deposition of the III₃-N layer may be similar tothe precursors used for the III₁-N layer and the III₂-N layer, i.e. NH₃is a suitable nitrogen precursor, TMG is a suitable gallium precursor,TEG is a suitable gallium precursor, TMA is a suitable aluminumprecursor, and TMI is a suitable indium precursor. A flow of one or morecarrier gases selected from the group of argon, nitrogen, hydrogen,helium, neon, xenon, and combinations thereof may also be included.

Optionally, after deposition of the III₃-N layer structure, processparameters suitable for growth of a III₄-N layer may be established.Such process parameters may include temperature, pressure, and the liketo define an environment within the processing chamber appropriate forthermal deposition of a nitride layer. Flows of III₄ and nitrogenprecursors are provided to deposit III₄-N structures on the substrate.The precursors include a nitrogen source and a source for a fourthgroup-III element such as Ga. For instance, suitable nitrogen precursorsinclude NH₃ and suitable Ga precursors include trimethyl gallium (“TMG”)and triethyl gallium (TEG). A flow of one or more carrier gases selectedfrom the group of argon, nitrogen, hydrogen, helium, neon, xenon, andcombinations thereof may also be included.

At block 448, the precursor flows are terminated. The substrate isremoved from the processing chamber without exposing the substrate toatmosphere at block 450.

At block 452 an optional post-deposition chamber clean is performed inwhich the interior of the processing chamber is exposed to a thirdcleaning gas to remove contaminants and Group-III containing depositsfrom the chamber and chamber components prior to the processing ofadditional substrates at block 454.

The processing conditions used for deposition of the III₁-N, III₂-N,III₃-N, and III₄-N layers may vary depending on specific applications.The following table provides exemplary processing conditions andprecursor flow rates that are generally suitable in the growth ofnitride semiconductor structures using the devices described above:

Parameter Value Temperature (° C.)   500-1,200 Pressure (torr)0.001-760   TMG flow (sccm)  0-50 TEG flow (sccm)  0-50 TMA flow (sccm) 0-50 TMI flow (sccm)  0-50 PH₃ flow (sccm)    0-1,000 AsH₃ flow (sccm)   0-1,000 NH₃ flow (sccm)    100-100,000 N₂ flow (sccm)     0-100,000H₂ flow (sccm)     0-100,000

As will be evident from the preceding description, a process might notuse flows of all the precursors in any given process. For example,growth of GaN might use flows of TMG, NH₃, and N₂ in one embodiment;growth of AlGaN might use flows of TMG, TMA, NH₃, and H₂ in anotherembodiment, with the relative flow rates of TMA and TMG selected toprovide a desired relative Al:Ga stoichiometry of the deposited layer;and growth of InGaN might use flows of TMG, TMI, NH₃, N₂, and H₂ instill another embodiment, with relative flow rates of TMI and TMGselected to provide a desired relative In:Ga stoichiometry of thedeposited layer.

EXAMPLE

The following example is provided to illustrate how the general processmay be used for the fabrication of compound nitride structures describedin connection with processing system 200. The example refers to a LEDstructure, with its fabrication being performed using a processingsystem 200 having one MOCVD chamber 202. In one embodiment, the LEDstructure is similar to structure 100. The cleaning and deposition ofthe initial GaN layers and deposition of the remaining InGaN, AlGaN, andGaN contact layers may be performed in the MOCVD chamber 202.

The process begins with a carrier plate 212 containing one or moresubstrates 340 being transferred into the MOCVD chamber 202. The MOCVDchamber 202 is configured to provide rapid deposition of GaN. Apretreatment process and/or buffer layer is grown over the substrate inthe MOCVD chamber 202 using MOCVD precursor gases. This is followed bygrowth of a thick u-GaN/n-GaN layer, which in this example is performedusing MOCVD precursor gases.

After deposition of the u-GaN and n-GaN layer, the carrier plate 212 istransferred out of the MOCVD chamber 202 and into either the loadlockchamber 208 or the batch loadlock chamber 209 without breaking vacuum,with the transfer taking place in a high-purity N₂ atmosphere via thetransfer chamber 206. After removal of the carrier plate 212, the MOCVDchamber 202 is cleaned with chlorine gas. In one embodiment, an emptycarrier plate 212 is inserted into the MOCVD chamber 202 prior tocleaning the chamber and exposed to the cleaning gas while cleaning theMOCVD chamber 202. After the MOCVD chamber 202 is cleaned, the carrierplate 212 is re-inserted into the MOCVD chamber 202 and the InGaNmulti-quantum-well (MQW) active layer is grown over the u-GaN and n-GaNlayer.

Optionally, in one embodiment, after the MQW active layer is grown, thecarrier plate 212 is transferred out of the MOCVD chamber 202 and intoeither the loadlock chamber 208 or the batch loadlock chamber 209without breaking vacuum, with the transfer taking place in a high-purityN₂ atmosphere via the transfer chamber 206. After removal of the carrierplate 212, the MOCVD chamber 202 is cleaned with chlorine gas.

After the MOCVD chamber 202 is cleaned, the carrier plate 212 isre-inserted into the MOCVD chamber 202 and the p-AlGaN layer and p-GaNlayer are deposited over the InGaN MQW active layer.

The completed structure is then transferred out of the MOCVD chamber 202so that the MOCVD chamber 202 is ready to receive an additional carrierplate 212 with unprocessed substrates. In one embodiment, the MOCVDchamber 202 may be exposed to a post-deposition chamber clean prior toprocessing additional substrates. The completed structure may either betransferred to the batch loadlock chamber 209 for storage or may exitthe processing system 200 via the loadlock chamber 208 and the loadstation 210.

In one embodiment, multiple carrier plates 212 may be individuallytransferred into and out of the MOCVD chamber 202 for deposition of theGaN layers, each carrier plate 212 may then be stored in the batchloadlock chamber 209 and/or the loadlock chamber 208 while the MOCVDchamber is cleaned. After the MOCVD chamber is cleaned, each carrierplate 212 may be individually transferred to the MOCVD chamber 202 fordeposition of the InGaN multi-quantum-well (MQW) active layer.

In certain embodiments, it may be desirable to clean the carrier plate212 along with the chamber. After the carrier plate 212 is removed fromthe MOCVD chamber 202, the substrates 340 are removed from the carrierplate 212 and the carrier plate is re-inserted into the MOCVD chamber202 for cleaning along with the MOCVD chamber 202.

Exemplary Cleaning Process:

FIG. 5 is a flow diagram of a cleaning process 500 that may be used forMOCVD chamber cleaning according to embodiments described herein. Atblock 502, the processing chamber is purged/evacuated to removecontaminants generated during the deposition process. Thepurge/evacuation process of block 502 is similar to the purge/evacuationprocess described below in block 506 and block 512. As shown in block504, a cleaning gas is flowed into a processing chamber. The cleaninggas may include any suitable halogen containing gas. Suitable halogencontaining gases include fluorine gas, chlorine gas, bromine gas, iodinegas, halides including HI gas, HCl gas, HBr gas, HF gas, NF₃, otherreactive elements, and combinations thereof. In one embodiment, thecleaning gas is chlorine gas (Cl₂). In one embodiment, the processingchamber is an MOCVD chamber similar to the chamber 202.

In certain embodiments, the flow rates in the present disclosure areexpressed as sccm per interior chamber volume. The interior chambervolume is defined as the volume of the interior of the chamber in whicha gas can occupy. For example, the interior chamber volume of chamber202 is the volume defined by the chamber body 302 minus the volumeoccupied therein by the showerhead assembly 304 and by the substratesupport assembly 314. In certain embodiments, the cleaning gas may beflowed into the chamber at a flow rate of about 500 sccm to about 10,000sccm. In one embodiment, the cleaning gas is flowed into the chamber ata flow rate from about 1,000 sccm to about 4,000 sccm. In oneembodiment, the cleaning gas is flowed into the chamber at a flow rateof about 2,000 sccm. In one embodiment, the cleaning gas may be flowedinto the chamber at a flow rate of about 12.5 sccm/L to about 250sccm/L. In one embodiment, the cleaning gas is flowed into the chamberat a flow rate from about 25 sccm/L to about 100 sccm/L. In oneembodiment, the cleaning gas is flowed into the chamber at a flow rateof about 50 sccm/L.

In one embodiment, the cleaning gas may be co-flowed with a carrier gas.The carrier gas may be one or more gases selected from the group ofargon, nitrogen, hydrogen, helium, neon, xenon, and combinationsthereof. In one embodiment, the carrier gas is flowed into the chamberat a flow rate from about 500 sccm to about 3,000 sccm. In oneembodiment, the carrier gas is flowed into the chamber at a flow rate offrom about 1,000 sccm to about 2,000 sccm. In one embodiment, thecarrier gas is flowed into the chamber at a flow rate from about 12.5sccm/L to about 75 sccm/L. In one embodiment, the carrier gas is flowedinto the chamber at a flow rate of from about 25 sccm/L to about 50sccm/L. In one embodiment, a total pressure of the chamber is from about0.001 Torr to about 500 Torr. In one embodiment, the total pressure ofthe chamber is from about 50 Torr to about 200 Torr. In one embodiment,the total pressure of the chamber is about 100 Torr. Lower pressure isgenerally favored to keep GaCl₃ in gaseous phase. In one embodiment, atemperature of the susceptor is from about 500° C. to about 700° C. Inone embodiment, the temperature of the susceptor is from about 550° C.to about 700° C. In one embodiment, the temperature of the susceptor isabout 650° C. In one embodiment, a temperature of the showerhead is fromabout 100° C. to about 200° C. The cleaning gas may be flowed into theprocessing chamber for a time period of about 2 minutes to about 10minutes. In one embodiment, the cleaning gas may be flowed into theprocessing chamber for a time period of about 5 minutes. It should beunderstood that several cycles of cleaning may apply with an optionalpurge process performed in between cleaning cycles. The time period ofcleaning gas flow should be generally long enough to remove galliumcontaining deposits, such as gallium and GaN deposits, from the surfaceof the chamber and the surface of the chamber components including theshowerhead. In one embodiment, a carrier gas may be flown in conjunctionwith the cleaning gas. The carrier gas may be one or more gases selectedfrom the group of argon, nitrogen (N₂), helium, neon, and xenon, amongothers. In one embodiment, the cleaning gas is a plasma containingcleaning gas. In one embodiment, the plasma containing cleaning gas isformed remotely using a remote plasma generator. In one embodiment, theplasma containing gas is formed in-situ within the processing chamber.

Referring to block 506, after the flow or pulse of the cleaning gas hasceased, the processing chamber is purged/evacuated to remove cleaningby-products generated during the cleaning process. The purge gas may beone or more purge gases selected from the group of argon, nitrogen,hydrogen, helium, neon, xenon, and combinations thereof may also beincluded. In one embodiment, the purge gas may be identical to theoptional carrier gas of block 504. In one embodiment, the processingchamber is purged by providing a purge gas at a flow rate of about 1,000sccm to about 7,000 sccm. In one embodiment, the purge gas is providedto the processing chamber at a flow rate from about 2,000 sccm to about4,000 sccm. In one embodiment, the processing chamber is purged byproviding a purge gas at a flow rate of about 25 sccm/L to about 175sccm/L. In one embodiment, the purge gas is provided to the processingchamber at a flow rate from about 50 sccm/L to about 160 sccm/L. In oneembodiment, the chamber may be maintained at a total chamber pressurefrom about 0.001 Torr to about 10 Torr. In one embodiment, the totalpressure of the chamber may be about 5 Torr. In one embodiment, atemperature of the susceptor is from about 600° C. to about 1,000° C. Inone embodiment, the temperature of the susceptor is about 900° C. In oneembodiment, a temperature of the showerhead is less than 100° C. In oneembodiment, the purge gas may be flowed into the processing chamber fora time period of about 5 minutes. The time period of purge gas flowshould be generally long enough to remove by-products of the cleaningprocess of block 504 from the processing chamber.

Alternatively, or in addition to introducing the purge gas, the processchamber may be depressurized in order to remove the residual cleaninggas as well as any by-products from the processing chamber. Thedepressurization process may result in the chamber pressure beingreduced to a pressure in the range of about 0.001 Torr to about 40 Torrwithin a time period of about 0.5 seconds to about 20 seconds.

In embodiments where a carrier gas is used in conjunction with thecleaning gas in block 504, the purge process of block 506 may beperformed by ceasing the flow of the cleaning gas while continuing toflow the carrier gas. Thus allowing the carrier gas to function as thepurge gas in the purge process of block 506.

As shown in block 508, after the processing chamber is purged/evacuatedat block 506 an optional cleaning gas is flowed into the processingchamber. The cleaning gas may include halogen containing gases such asfluorine gas, chlorine gas, iodine gas, bromine gas, HI gas, HCl gas,HBr gas, HF gas, NF₃, other reactive elements, and combinations thereof.In one embodiment, the cleaning gas is chlorine gas (Cl₂). In oneembodiment, the cleaning gas in block 508 is identical to the cleaninggas used in block 504. In another embodiment, the cleaning gases used inblock 504 and block 508 are different cleaning gases.

In one embodiment, the cleaning gas may be flowed into the chamber at aflow rate from about 1,000 sccm to about 10,000 sccm. In one embodiment,the cleaning gas may be flowed into the chamber at a flow rate fromabout 3,000 sccm to about 5,000 sccm. In one embodiment, the cleaninggas may be flowed into the processing chamber at a flow rate of about4,000 sccm. In one embodiment, the cleaning gas may be flowed into thechamber at a flow rate from about 25 sccm/L to about 250 sccm/L. In oneembodiment, the cleaning gas may be flowed into the chamber at a flowrate from about 75 sccm/L to about 125 sccm/L. In one embodiment, thecleaning gas may be flowed into the processing chamber at a flow rate ofabout 100 sccm/L. As discussed above, a carrier gas may optionally beco-flowed in conjunction with the cleaning gas. The carrier gas may beone or more gases selected from the group of argon, nitrogen, hydrogen,helium, neon, xenon, and combinations thereof. In one embodiment, thecarrier gas is flowed into the chamber at a flow rate from about 1,000sccm to about 5,000 sccm. In one embodiment, the carrier gas is flowedinto the chamber at a flow rate from about 2,000 sccm to about 3,000sccm. In one embodiment, the carrier gas is flowed into the chamber at aflow rate from about 25 sccm/L to about 125 sccm/L. In one embodiment,the carrier gas is flowed into the chamber at a flow rate from about 50sccm/L to about 75 sccm/L. In one embodiment, the chamber may bemaintained at a total chamber pressure of about 300 Torr to about 700Torr. In one embodiment, the chamber may be maintained at a totalchamber pressure of about 600 Torr. In one embodiment, a temperature ofthe susceptor is about 400° C. to about 600° C. In one embodiment, thetemperature of the susceptor is about 420° C. In one embodiment, atemperature of the showerhead is greater than 200° C. In one embodiment,the showerhead temperature is greater than 260° C., for example, fromabout 260° C. to about 400° C. The cleaning gas may be flowed into theprocessing chamber for a time period of about 2 minutes to about 10minutes. In one embodiment, the cleaning gas may be flowed into theprocessing chamber for a time period of about 3 minutes.

As shown in block 510, after flowing the cleaning gas into theprocessing chamber, an optional soak process may be performed. Duringthe soak process, the flow of cleaning gas is reduced while thesusceptor temperature, showerhead temperature, and the chamber pressuremay be maintained. In one embodiment, the flow rate of the cleaning gasmay be reduced relative to the flow rate in block 508 to between about250 sccm to about 1,000 sccm. In one embodiment, the flow rate of thecleaning gas may be reduced to about 500 sccm. In one embodiment, theflow rate of the cleaning gas may be reduced relative to the flow ratein block 508 to between about 6.25 sccm/L to about 25 sccm/L. In oneembodiment, the flow rate of the cleaning gas may be reduced to about12.5 sccm/L. In one embodiment, a total pressure of the chamber is fromabout 300 Torr to about 700 Torr. In one embodiment, the total pressureof the chamber is about 600 Torr. In one embodiment, the susceptortemperature is from about 400° C. to about 600° C. In one embodiment,the susceptor temperature is about 420° C. In one embodiment, atemperature of the showerhead is greater than 200° C. In one embodiment,the showerhead temperature is greater than 260° C., for example, fromabout 260° C. to about 400° C. The soak process may be performed for atime period of about 1 minute to about 5 minutes. In one embodiment, thesoak process may be performed for a time period of about 2 minutes.

Referring to block 512, after the optional soak process, the processingchamber may be purged/evacuated to remove cleaning by-products generatedduring the soak and cleaning processes. The purge gas may be one or morepurge gases selected from the group of argon, nitrogen, hydrogen,helium, neon, xenon, and combinations thereof. In one embodiment, thepurge gas may be identical to the optional carrier gas of block 510. Inone embodiment, the processing chamber is purged by providing a purgegas at a flow rate of about 1,000 sccm to about 4,000 sccm. In oneembodiment, the purge gas may be flowed into the processing chamber at aflow rate of about 3,000 sccm. Optionally, during the purge process thecleaning gas may be flowed into the chamber at a flow rate from about2,000 sccm to about 6,000 sccm. In one embodiment, the cleaning gas maybe flowed into the chamber at a flow rate of about 4,000 sccm. In oneembodiment, the processing chamber is purged by providing a purge gas ata flow rate of about 25 sccm/L to about 100 sccm/L. In one embodiment,the purge gas may be flowed into the processing chamber at a flow rateof about 75 sccm/L. Optionally, during the purge process the cleaninggas may be flowed into the chamber at a flow rate from about 50 sccm/Lto about 150 sccm/L. In one embodiment, the cleaning gas may be flowedinto the chamber at a flow rate of about 100 sccm/L. In one embodiment,the cleaning gas is co-flowed with the purge gas. In one embodiment, thetotal chamber pressure is from about 0.001 Torr to about 10 Torr. In oneembodiment, the total chamber pressure is about 5 Torr. In oneembodiment, the susceptor temperature is from about 400° C. to about600° C. In one embodiment, the susceptor temperature is about 430° C. Inone embodiment, the showerhead temperature is greater than 200° C. Inone embodiment, the showerhead temperature is greater than 260° C., forexample, from about 260° C. to about 400° C. The soak process may beperformed for a time period of about 1 minute to about 5 minutes. In oneembodiment, the soak process may be performed for a time period of about2 minutes. In one embodiment, the purge gas may be flowed into theprocessing chamber for a time period of about 5 minutes. The time periodof purge gas flow should be generally long enough to remove by-productsof the cleaning process of block 508 and the soak process of block 510from the processing chamber.

In one embodiment, either or both of the purge processes of block 502,block 506, and block 512 may be performed with a nitrogen containing gassuch as ammonia (NH₃) at an elevated temperature (>1,000° C.) to reducethe amount of residual GaCl₃ in the processing chamber after thecleaning process. Optionally, a chamber bake process may be performedafter any of the aforementioned purge processes in a nitrogen and/orhydrogen containing atmosphere at a high temperature from about 950° C.to about 1,050° C. at a low pressure from about 0.001 Torr to about 5Torr to ensure that any residual deposition from the chamber cleanprocess leave the chamber completely. Other aspects or exemplarycleaning processes are described in U.S. patent application Ser. No.12/244,440, now published as US 2009-0149008, titled METHOD FORDEPOSITING GROUP III/V COMPOUNDS, filed Oct. 2, 2008, which is herebyincorporated by reference in its entirety.

FIG. 6A is a plot demonstrating In X-Ray Fluorescence for indium (In)distribution across the surface of a substrate for In deposited usingprior art processes. FIG. 6B is a plot demonstrating In X-RayFluorescence for In distribution across the surface of a substrate forIn deposited according to embodiments described herein. With referenceto FIGS. 6A and 6B, the x-axis represents location relative to thecenter of the substrate in millimeters (mm) and the y-axis representsindium X-ray fluorescence intensity. The prior art process used toobtain the results depicted in FIG. 6A was an in-situ process where aGaN layer and InGaN layers were deposited in the same chamber withoutthe benefit of the split process methods described herein. The processused to obtain the results depicted in FIG. 6B was performed using anin-situ process wherein a chamber clean was performed after formation ofthe GaN layer and prior to the deposition of the InGaN layer within thesame chamber. The results depicted in FIG. 6B show a more uniformdistribution of indium across the substrate for a single chamber splitprocess with a chamber clean after high-temperature GaN deposition (bothuGaN and nGaN) prior to MQWs growth in comparison with the resultsdepicted in FIG. 6A obtained using the prior art process.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An integrated processing system for manufacturing compound nitridesemiconductor devices comprising: a metal organic chemical vapordeposition (MOCVD) chamber operable to form a gallium nitride (GaN)layer over one or more substrates with a thermalchemical-vapor-deposition process and to form a multi-quantum well (MQW)layer over the GaN layer; and a halogen containing gas source coupledwith the MOCVD chamber operable for flowing a halogen containing gasinto the MOCVD chamber to remove at least a portion of unwanteddeposition build-up deposited when forming the GaN layer over the one ormore substrate from one or more interior surfaces of the MOCVD chamberprior to forming the MQW layer over the GaN layer, wherein the halogencontaining gas is selected from the group comprising fluorine, chlorine,bromine, iodine, HI gas, HCl gas, HBr gas, HF gas, NF₃, and combinationsthereof.
 2. The integrated processing system of claim 1, furthercomprising: a purge gas source coupled with the MOCVD chamber operablefor flowing purge gas into the MOCVD chamber to remove reactionby-products formed from the reaction of the halogen containing gas withthe unwanted deposition build-up from the MOCVD chamber prior to formingthe MQW layer over the GaN layer.
 3. The integrated processing system ofclaim 1, further comprising: a transfer region in transferablecommunication with the MOCVD chamber; a robot assembly disposed in thetransfer region for transferring the one or more substrates withoutexposing the one or more substrates to atmosphere; a loadlock chamber intransferable communication with the transfer region, whereintransferring one or more substrates comprises transferring the one ormore substrates from the MOCVD chamber to a loadlock chamber withoutexposing the substrate to atmosphere in an environment having greaterthan 90% N₂.